This disclosure generally relates to passenger aircraft that have passengers seated proximate to a fuselage sidewall and behind respective fuselage frames, and more particularly to fuselage frames configured to have additional functionalities.
A fuselage of a passenger aircraft is typically constructed with a fuselage skin structurally connected to a skeleton structure that includes a series of spaced-apart, hoop-shaped frames. The hoop-shaped frames define the aircraft cross section at locations along the longitudinal length of the fuselage. A passenger cabin (hereinafter “cabin”) is formed inside the fuselage by supplying a deck (i.e., floor) and a ceiling, and covering the interior sides of the fuselage with decorative interior side panels. In some aircraft, in addition, a multiplicity of windows are formed through the interior side panels and fuselage skin, and located adjacent at least some of the window seats. Passenger aircraft also include an environmental control system (or ECS) that includes a distribution duct in a crown of the fuselage above the cabin ceiling, riser ducts extending from the distribution duct downward along the fuselage sidewall to a supply duct and/or an air conditioning pack (A/C pack) below the cabin deck to channel air from the supply duct and/or A/C pack to the distribution duct. The riser ducts are individual ducts positioned at locations along the longitudinal length of the fuselage and between the fuselage skin and the interior side panels (sometimes around the windows).
Fuselage configurations are known in which a multiplicity of frames are spaced apart along a longitudinal axis of the fuselage in accordance with a specified frame pitch, while the cabin contains a multiplicity of rows of seats separated according to a seat pitch. The seat pitch may be indexed to the frame pitch such that window seats are located between adjacent frames to permit a reduced-perimeter (i.e., reduced-width) aircraft fuselage. For example, in one known exemplary reduced-perimeter fuselage configuration, outboard portions of the window seats occupy respective portions of the spaces between adjacent frames (hereinafter “inter-frame spaces”).
For aircraft having window seats that project at least partially into respective inter-frame spaces, there is reduced and often insufficient space between the fuselage skin and interior side panels to locate conventional ECS riser ducts, riser ducts used for wiring and other aircraft components that are usually positioned between the fuselage skin and the interior side panels. This window seat arrangement also puts the window seat passenger closer to the fuselage frame, raising some concern that such a seating arrangement would not satisfy Head Impact Criteria (HIC) for certification.